/Engine/Source/Runtime/Engine/Classes/GameFramework/Actor.h
TInlineComponentArrayis simply aTArraythat reserves a fixed amount of space on the stack to try to avoid heap allocation when there are fewer than a specified number of elements expected in the result.
template<class T, uint32 NumElements> class TInlineComponentArray : public [TArray< T, TInlineAllocator< NumElements > >](API\Runtime\Core\Containers\TArray)